Vacuum sealing can



Dec. 17, 1935. DARUNG I 2,024,512.

VACUUM SEALING CAN Filed May 29, 1935 ATMOSPHERIC,

PRESSURE Patented Dec. 1 7," 1935 2,024,512 VACUUM SEALING can Frank L. Darling, Douglaston, N. Y., assig'nor, by

mesne assignments, to Glen-Dar Can 00., a corporation of Delaware Application May 29, 1935, Serial NCO. 24,124

. 5 Claims.

My present invention relates to certain new and useful improvements in vacuum sealing cans, especially useful for packing coffee, malted milk, and other granular or powdered substances.

More especially, the present invention has for its object to provide certain improvements in the can described in-and comprising the subject matter of my application Serial No. 20,838.' Experiments have shown that in vacuumized cans whose heads are stamped initially flat, .i. e., as plane discs, and as such are secured to the can body, the heads draw inwardly under atmospheric pressure when vacuumizing .(see, for instance, Figures 3 and 4 of the drawings of the patent to Williams No. 812,968, issued February 20, 1906). This not only tends to loosen the bead from the annular can body s'o-that leaks may occur in the joint, but it also tends to produce leaks at the plugclosure. I find that these deficiencies or defects can be overcome by what I term pre-forming the heads by stamping or otherwise giving to them substantially the form that the straight.

discs would assume on vacuumizing and sealing the can.

. Further, with the straight or flat can heads such as shown in my application aforesaid, when the plugs are being inserted by applied pressure the heads are forced to bow inwardly, since the plugs aremade to fit tightly the can head opening; this adds to the tendency to pulland open the annular joint between the body and the head of the can, and consequently increases the danger of leakage. I

Experiments have shown, however, that when the head is pre-formed, i. e., stamped to its set" concaviture before it is secured to the body, the head will withstand the plug-closure applying forces to a far greater degree than is the case with initially flat heads; in fact the plug-closure applying forces do not substantially increase the concaviture of the -pre-formed head.

Again, by forming the head dished to its ultimate degree the periphery of the head necessarily becomes a fixed annulus against the can wall; force within the can (as generated by gas pressure from freshi'coifee) will tend, not to loosen, but to tighten the peripheral joint. be-' tween the can head and the can body and further, because of the peculiar formation of the head opening and the fixed diameter of the plug forced therein, there will be a tendency to tighten the grip of the can head flange on the plug itself when internal pressures become established and thereby tend to increase the sealing effect.

I drawing, in which:

Other objects will in part be obvious and in part be pointed out hereinafter.

To the attainment of the aforesaid objects and ends the invention still further resides in the novel details of construction, combination and ,arrange- 5 ment of parts, all of which will be fully'described in the following detailed description, and then be particularly pointed out in the appended claims, reference being had to the accompanying Figure 1 is a vertical longitudinal section of a can embodying my present invention with the plug-closure in place, sealed.

Figure 2 is a detail diagrammatic vertical sectional view of a flat head can showing the posi- 15 tion of the upstanding flange before inserting the plug-closure, the plug-closure being indicated in dotted lines.

I Figure 3 is a view similar to Figure 2 after vacuumizing, and after. the plug-closure has been 20 inserted. v

Figure 4 is a similar view showing the same can after the head is popped out by accumulated pressure within the. can and before the plugclosure blows oif.

In the drawing, l represents a can having, a bottom 2 and a top or head 3 the latter, in the present case, being stamped or otherwise shaped to the final form of a flat head disc under vacuumizing and plug-closure inserting pressures, i. e., 30 it is pre-formed as a concaved or disked plate whose periphery I5 is tightly secured to the can body by the usual rolling or seaming process.-

The head 3 has an opening or mouth bound by an upwardly and outwardly flared flange 4. Sur- 5 rounding the flange 4 and spaced a suitable displug-type closure member seats.

The plug-type closure member has an annular wall l3 and an annular crown or upstanding bead 8 constituting on its under side a groove to receive a suitable plastic sealing substance It. The

outer edge of the closure is extended upwardly and is outwardly flared to provide a rim l I from the edge of which extends a plurality (preferably three) of preferably diamond-shaped points III which overlie and rest on the bead 6 when the I plug is in place.-

When the closure plug 1 is placed in the hole in the top 3 of the can and is drawn down by reason of the partial vacuum in the can (or is forced down by pressure from above), the

points II! will contact the bead 5 and the plastic I 4- will be compacted in the V-shaped annular space l2 between the wall i3 and the flange 4 and act somewhat as an elastic wedge to effect a tight or hermetic seal between the closure and the can head. The depth of the supporting portion 9 of the plug is such that it will come to rest before the edge of the flange 3 passes entirely through the plastic. This insures the edge of the flange being always covered and protected by the plastic compound and the edge will never come into contact with the metal of the closure.

In practice the lid 3 and the closure 71 are heavily tinned so that the points I0 may be united to the head 5 at their points of contact by spotheating treatment, heat being applied until the tin of the lid and that of the points flows together and thereby secures the closure to the can without the use of solder. Of course, solder may be used, if desired.

This renders the can safe against tampering with, for if the adhesion between the points it;

and the bead 5 be broken, that will indicate at once the fact that the can has been tampered with.

As the points if? arepr'eferably only secured at their extremities, they offer very little resistance to the removal of the closure. To remove the closure it is only necessary to insert the blade of a knife between the rim or flange l l and the bead 5, and use the blade as a lever to prize up the closure. The closure having been once removed from the can top opening, it may be replaced as a temporary closure in the event that all the contents of the can are not emptied out or used in the first place. The plasticity of the compound M is such that it will yield to rc-embed the flange 3 when the closure is pressed down.

By reason of the facts that the flange 43 flares outwardly, the bottom of the plug lies below the 1 plane of the top 3 when the plug is in place, and

the wall J3 is slightly resilient, the plug will fit the mouth or opening of the can with a snug frictional engagement that prevents the plastic it being sucked into the can by the vacuum.

Practice has demonstrated that fresh coffee,

vacuum packed, does not hold the vacuum because the gases given off by the coffee often build up a positive pressure within the can. Unless this pressure is relieved it causes the ends of the cans to bulge and sometimes results in the explosion of the can. Ordinarily the pressure which builds up in canned fresh coffee does not go beyond the limits of from three to five pounds. The lower pressures are not harmful, but pressures around five pounds bulge the can ends too much, so they will not set fiat. By my construction the area of the plug opposed to internal pressure and the tenacity of the union between the points Ill and the bead 5 are so designed that only pressures above a danger point (say, nine pounds) will cause the plug to blow out and become detached from the can.

In practice a closure plug 1 having a diameter of approximately two inches with three points Ill attached to the head 5 in the manner before described will permit venting at five pounds and will blow off at about nine pounds internal can pressure. The resiliency of the material of the plug is sufficient to restore the plug to a position to reseal the can after venting has reduced the internal pressure to less than five pounds.

The pressures above mentioned are illustrative only, as by varying the resiliency of the material of the closure points and the tenacity of their union to the bead 5 different pressure values may be taken care of.

By providing the channel at 6 between the bead 5 and flange 4, should some of the material be spilled in filling the can, this material will not 5 collect in the space between the flange 4 and the wall I3 of the plug but will drop into the channel 6. Thus, none of the material will prevent a tight metal-tometal contact between the wall It and the bend of the flange l throughout the n entire circumference of the wall I 3, or between the compound and the cut edge of the can. Thus the spilled material can not prevent an air-tight seal being effected. In the present day practice, where the cans are filled and then the heads are 15 put on by rolling, it frequently happens that some of the material gets rolled into the seam and when that occurs the can often leaks. With my invention this objectionable feature is eliminated.

In virtue of my invention it will be seen that a 34; simple, effective and inexpensive closure has been provided which is economical to manufacture and operate and will readily serve its intended purposes.

A comparison of Figures 1 and 3 of the accompanying drawing will illustrate the difference between a can head that is pre-formed and one which assumes its final shape under stress. As will be seen by reference to Figure 1, the plastic material is not squeezed out by a narrowing of the 30 V-shaped recess l2, as is the case 'in Figure 3. In Figures 2, 3, and 4, which represent the can head of my application aforesaid, those parts which correspond to similar parts in my present invention (Figure 1) bear the same reference numerals, plus the index letter a.

With the can head of my previous application aforesaid the dishing under vacuumlzing and closureapplying pressures (see Figure 3) or under excessive internal pressures (see Figure 4), 40 there is a tendency to pull the seam l5a at the places marked with the arrows A, whereas with the pre-formed head (see Figure 1) of my present application this tendency is absent.

When in this application I make reference to a pre-formed head I desire that term to be construed as having reference to a head stamped or otherwise formed to the shape which a fiat head would assume upon vacuumizing (to the extent necessary for the product) and sealing the 50 can, or, in other words, a head which has been dished or concaved to the form or shape where it will remain constant after being secured in place to the can body.

By pre-forming the can head or top by dies, before roiling it into the can body, I am enabled to get a perfect seal at the point indicated by the arrows A, and the plug is enabled to assume its proper relation to the sealing compound and the soldering points under action of the vacuum;

pre-forming the can head has'a hardening effect 60 on the material thereof, tending to stiffen it considerably and forming a brace against the can body at the point indicated by the arrows A.

'Actual tests show that the head will not push through the center under the normal gas pressures built up by the gases of the coffee when the head is pre-formed. In addition to these many advantages, I find that the head will withstand a pressure of pounds while inserting the plug without depressing to a noticeable degree, where- 70 as in inserting the plug with a flat top, the top will press down at least one-fourth of an inch under thirty pounds pressure, a pressure not sulficient to effect a good seal between the plug and the head, and at the same time the head will 00- N to those skilled in the art to which it appertains.

What Iclaim is: a 1; In a can, a metallic head having an opening bounded by an upwardly and outwardly flared flange, a plu -type closure fitting into said opening and having an annular channel containing a plastic sealing substance to fit over said flange and embed the edge 01' said flange in the sealing substance, and means to arrest the insertion of -saidclosure before the edge oi said flange passes through the plastic, said head being pre-shaped to its normal form under vacuum.

2. In a can, a metallic head having an opening bounded by anupwardly and outwardly flared flange, a plug-type closure fitting into said opening and having an annular channel containing a plastic sealing substance to fit over said flange and embed the edge of said flange in the sealing substance, said closure having an annular supporting portion surrounding said channel 'to engage the can-before the edge of said fiange passes through the plastic whereby said edge is always protected by the plastic, said head being pre-shaped to its 110111181 form under vacuum.

3. In a can, a metallic headhaving an opening bounded by an upwardly and outwardly flared flange, a plug-type closure fitting into said opening and having an annular channel containing a plastic sealing substance to flt over said flange and embed the edge of said flange in the sealing substance, said can' having an annular outwardly projecting bead surrounding said flange and spaced from the same, and said closure having a rim with points projecting therefrom, the points overlying said bead, and means to= unite said points and said bead, said head being pre-shaped to its normal form under vacuum;

4. In a can, a metallic head having a filling opening bounded by an upwardly and outwardly flared flange having a cut edge, a plug-type closure fitting into said opening and having an annular channel containing a plastic sealing substance to fit over said-fiarige and embed the edge of said flange in the sealing substance, said closure having an annular supporting portion surrounding said channel to engage the can before the edge of said flange passes through the plastic whereby said edge is always protected from corrosion by the plastic, said head being pre-shaped to its normal form under vacuum.

'5. In combination with a can having a metallic head provided with a filling opening, a plug-type closure for said opening, and means cooperative with said closure to seal the can against ingress of air while permitting said closure itself to function as apressure-relief valve to relieve pressures up to a given degree, and thereafter to reseal the can, said head being pre-shaped to its 30 normal form under vacuum said means being wholly'located below a plane containing the top edge 01 the can. FRANK L. DARLING. 

